INTERNET-DRAFT D. Eastlake
Intended status: Proposed Standard Futurewei Technologies
Z. Li
S. Zhuang
Huawei Technologies
Expires: October 26, 2020 April 27, 2020
EVPN VXLAN Bypass VTEP
Abstract
A principal feature of EVPN is the ability to support multihoming
from a customer equipment (CE) to multiple provider edge equipment
(PE) with all-active links. This draft specifies a mechanism to
simplify PEs used with VXLAN tunnels and enhance VXLAN Active-Active
reliability.
Status of This Memo
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Table of Contents
1. Introduction............................................3
1.1 Terminology and Acronyms...............................3
2. VXLAN Gateway High Reliability..........................4
3. Detailed Problem and Solution Requirement...............6
4. The Bypass VXLAN Extended Community Attribute...........7
5. Control Plane Processing................................9
6. Data Packet Processing................................10
6.1 Layer 2 Unicast Packet Forwarding.....................10
6.1.1 Uplink..............................................10
6.1.2 Downlink............................................10
6.2 BUM Packet Forwarding................................11
7. IANA Considerations....................................12
7.1 IPv4 Specific.........................................12
7.2 IPv6 Specific.........................................12
8. Security Considerations................................13
Acknowledgements..........................................13
Contributors..............................................14
Normative References......................................14
Informative References....................................14
Authors' Addresses........................................15
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1. Introduction
A principal feature of EVPN is the ability to support multihoming
from a customer equipment (CE) to multiple provider edge equipment
(PE) with links used in the all-active redundancy mode. That mode is
where a device is multihomed to a group of two or more PEs and where
all PEs in such a redundancy group can forward traffic to/from the
multihomed device or network for a given VLAN [RFC7209]. This draft
specifies a VXLAN gateway mechanism to simplify PE processing in the
multi-homed case and enhance VXLAN Active-Active reliability.
1.1 Terminology and Acronyms
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
This document uses the following acronyms and terms:
All-Active Redundancy Mode - When a device is multihomed to a group
of two or more PEs and when all PEs in such redundancy group can
forward traffic to/from the multihomed device or network for a
given VLAN.
BUM - Broadcast, Unknown unicast, and Multicast.
CE - Customer Edge equipment.
DCI - Data Center Interconnect.
ESI - Ethernet Segment Identifier - A unique non-zero identifier that
identifies an Ethernet segment.
NVE - Network Virtualization Edge.
PE - Provider Edge equipment.
Single-Active Redundancy Mode - When a device or a network is
multihomed to a group of two or more PEs and when only a single PE
in such a redundancy group can forward traffic to/from the
multihomed device or network for a given VLAN.
VTEP - VXLAN Tunnel End Point.
VXLAN - Virtual eXtensible Local Area Network [RFC7348].
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2. VXLAN Gateway High Reliability
One example of the current situation would be a DCI (data center
interconnect) using VXLAN tunnels that is multihomed for reliability
as show in Figure 1. Each PE as a VXLAN Tunnel End Point (VTEP) uses
a different IP adress. Thus each PE must process EVPN updates based
on the ESIs [RFC7432].
.........
. DCI .
+----------+ . . +----------+
| PE +---------------------+ PE |
|VTEP IP-1 +--- . VXLAN . ---+VTEP IP-3 |
+----------+ \ .Tunnels. / +----------=
/ | ----- ----- | \
+--+ | . \ / . | +--+
|CE| | . X . | |CE|
+--+ | . / \ . | +--+
\ | ----- ----- | /
+----------+ / . VXLAN . \ +----------+
| PE +--- .Tunnels. ---+ PE |
|VTEP IP-2 +---------------------+VTEP IP-4 |
+----------+ . . +----------+
.........
Figure 1. Current Situtation
The situation is greatly simplified if the set of VTEPs connected to
a particular Ethernet segment all use the same anycast IP address.
PEs no longer need to conern themselves with whether a remote CE is
single or multi-homed. The situation is as shown in Figure 2. The IP
address within each VTEP group is synchronized by messages within
that group.
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.........
. DCI .
+----------+ . . +----------+
| Anycast | . . | Anycast |
|VTEP IP-1 +--- . . ---+VTEP IP-2 |
+----------+ \ . . / +----------=
/ ^ \ . . / ^ \
+--+ | \. ./ | +--+
|CE| Sy|nc >-------< Sy|nc |CE|
+--+ | /. VXLAN .\ | +--+
\ v / . Tunnel. \ v /
+----------+ / . . \ +----------+
| Anycast +--- . . ---+ Anycast |
|VTEP IP-1 | . . |VTEP IP-2 |
+----------+ . . +----------+
.........
Figure 2. Situtation Using Anycast
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3. Detailed Problem and Solution Requirement
In the scenario illustrated in Figure 3, where an enterprise site and
a data center are interconnected, the VPN gateways (PE1 and PE2) and
the enterprise site (CPE) are connected through a VXLAN tunnel to
provide L2/L3 services between the enterprise site (CPE) and data
center. The data center gateway (CE1) is dual-homed to PE1 and PE2
to access the VXLAN network, which enhances network access
reliability. When one PE fails, services can be rapidly switched to
the other PE, minimizing the impact on services.
As shown in Figure 3, PE1 and PE2 use a virtual address as a Network
Virtualization Edge (NVE) interface address at the network side,
namely, the Anycast VTEP address. In this way, the CPE is aware of
only one remote NVE interface and establishes a VXLAN tunnel with the
virtual address. The packets from the CPE can reach CE1 through
either PE1 or PE2. However, single-homed CEs may exist, such as CE2
and CE3. As a result, after reaching a PE, the packets from the CPE
may need to be forwarded by the other PE to a single-homed CE.
Therefore, a bypass VXLAN tunnel needs to be established between PE1
and PE2. An EVPN peer relationship is established between PE1 and
PE2. Different addresses, namely, bypass VTEP addresses, are
configured for PE1 and PE2 so that they can establish a bypass VXLAN
tunnel.
+-----+
---------------- | CPE |
^ +-----+
| / \
| / \
VXLAN Tunnel / \
| / \
| / Anycast \
v +-----+ VTEP +-----+
--------- | PE1 |------| PE2 |
+-----+ +-----+
/\ /\
/ \ / \
/ \ Trunk / \
/ \ / \
/ +\---/+ \
/ | \ / | \
/ +--+--+ \
/ | \
+-----+ +-----+ +-----+
| CE2 | | CE1 | | CE3 |
+-----+ +-----+ +-----+
Figure 3. Basic networking of the VXLAN active-active scenario
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4. The Bypass VXLAN Extended Community Attribute
This sections describes the extensions specified to meeting the
requirements given in Section 3 and enhance VXLAN active-active
reliability.
This document specifies two new BGP extended communities, called the
Bypass VXLAN Extended Community. The extended communities have a
Type indicating they are transitive and are IPv4-address-specific or
IPv6-address-specific, depending on whether the VTEP address to be
accommodated is IPv4 or IPv6. In the new extended communities, the
4-byte or 16-byte global administrator field encodes the IPv4 or IPv6
address that is the VTEP address and the 2-byte local administrator
field is formatted as shown in Figures 4 and 5.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x01 | Sub-Type=TBA1 | IPv4 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Address (cont.) | Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4. IPv4-address-specific Bypass VXLAN Extended Community
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type=0x00/0x40| Sub-Type=TBA2 | Target IPv6 Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target IPv6 Address (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target IPv6 Address (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target IPv6 Address (cont.) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Target IPv6 Address (cont.) | Flags | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5. IPv6-address-specific Bypass VXLAN Extended Community
Where
Type:
0x01 = type for IPv4 specific use.
0x00 = type for transitive IPv6 specific use.
0x40 = type for non-transitive IPv6 specific use.
Sub-Type:
TBA1 = subtype for IPv4 specific use.
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TBA2 = subtype for IPv6 specific use.
IPv4/IPv6: An address of that type.
Flags: MUST be sent as zero and ignored on receipt.
Reserved: MUST be sent as zero and ignored on receipt.
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5. Control Plane Processing
Using the topology in Figure 3:
1) PE2 sends a multicast route to PE1. The source address of the
route is the Anycast VTEP address shared by PE1 and PE2. The
route carries the bypass VXLAN extended community attribute,
including the bypass VTEP address of PE1.
2) After receiving the multicast route from PE2, PE1 considers that
an Anycast relationship be established with PE2. This is because
the source address (Anycast VTEP address) of the route is the same
as the local virtual address of PE1 and the route carries the
bypass VTEP extended community attribute. Based on the bypass
VXLAN extended attribute of the route, PE1 establishes a bypass
VXLAN tunnel to PE2.
3) PE1 learns the MAC address of the CEs through upstream packets
from the CEs and advertises them as routes to PE2 through BGP
EVPN. The routes carry the ESI of the links accessed by the CEs,
and information about the VLANs that the CE access, and the bypass
VXLAN extended community attribute.
4) PE1 learns the MAC address of the CPE through downstream packets
at the network side, specifies that the next-hop address of the
MAC route can be iterated to a static VXLAN tunnel, and advertises
the route to PE2. The next-hop address of the MAC route cannot be
changed.
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6. Data Packet Processing
This section describes how Layer 2 unicast and BUM (Broadcast,
Unknown unicast, and Multicast) packets are forwarded. A description
of how Layer 3 packets transmitted on the same subnet and Layer 3
packets transmitted across subnets cases are forwarded will be
provided in a furture version of this document.
6.1 Layer 2 Unicast Packet Forwarding
The following two subsections discuss Layer 2 unicast forwarding in
the topology shown in Figure 3.
6.1.1 Uplink
After receiving Layer 2 unicast packets destined for the CPE from
CE1, CE2, and CE3, PE1 and PE2 search for their local MAC address
table to obtain outbound interfaces, perform VXLAN encapsulation on
the packets, and forward them to the CPE.
6.1.2 Downlink
After receiving a Layer 2 unicast packet sent by the CPE to CE1, PE1
performs VXLAN decapsulation on the packet, searches the local MAC
address table for the destination MAC address, obtains the outbound
interface, and forwards the packet to CE1.
After receiving a Layer 2 unicast packet sent by the CPE to CE2, PE1
performs VXLAN decapsulation on the packet, searches the local MAC
address table for the destination MAC address, obtains the outbound
interface, and forwards the packet to CE2.
After receiving a Layer 2 unicast packet sent by the CPE to CE3, PE1
performs VXLAN decapsulation on the packet, searches the local MAC
address table for the destination MAC address, and forwards it to PE2
over the bypass VXLAN tunnel. After the packet reaches PE2, PE2
searches the destination MAC address, obtains the outbound interface,
and forwards the packet to CE3.
The process for PE2 to forward packets from the CPE is the same as
that for PE1 to forward packets from the CPE with the roles of CE2
and CE3 swapped.
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6.2 BUM Packet Forwarding
Using the topology in Figure 3, if the destination address of a BUM
packet from the CPE is the Anycast VTEP address of PE1 and PE2, the
BUM packet may be forwarded to either PE1 or PE2. If the BUM packet
reaches PE2, PE2 sends a copy of the packet to CE3 and CE1. In
addition, PE2 sends a copy of the packet to PE1 through the bypass
VXLAN tunnel between PE1 and PE2. After the copy of the packet
reaches PE1, PE1 sends it to CE2, not to the CPE or CE1. In this
way, CE1 receives only one copy of the packet.
Using the topology in Figure 3, after a BUM packet from CE2 reaches
PE1, PE1 sends a copy of the packet to CE1 and the CPE. In addition,
PE1 sends a copy of the packet to PE2 through the bypass VXLAN tunnel
between PE1 and PE2. After the copy of the packet reaches PE2, PE2
sends it to CE3, not to the CPE or CE1.
Using the topology in Figure 3, after a BUM packet from CE1 reaches
PE1, PE1 sends a copy of the packet to CE2 and the CPE. In addition,
PE1 sends a copy of the packet to PE2 through the bypass VXLAN tunnel
between PE1 and PE2. After the copy of the packet reaches PE2, PE2
sends it to CE3, not to the CPE or CE1.
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7. IANA Considerations
IANA is requested to assign two new Extended Community attribute
SubTypes as follows:
7.1 IPv4 Specific
Sub-Type Value Name Reference
-------------- ------------------------------- ----------
TBA1 Bypass VXLAN Extended Community [this doc]
7.2 IPv6 Specific
Sub-Type Value Name Reference
-------------- ------------------------------- ----------
TBA2 Bypass VXLAN Extended Community [this doc]
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8. Security Considerations
TBD
For general EVPN Security Considerations, see [RFC7432].
Acknowledgements
The authors would like to thank the following for their comments and
review of this document:
TBD
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Contributors
The following individuals made significant contributions to this
document:
Haibo Wang
Huawei Technologies
Huawei Bldg., No. 156 Beiqing Road
Beijing 100095
China
Email: rainsword.wang@huawei.com
Normative References
[RFC2119] - Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119,
March 1997, .
[RFC7432] - Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A.,
Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based
Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 2015,
.
[RFC8174] - Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May
2017, .
Informative References
[RFC7209] - Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N.,
Henderickx, W., and A. Isaac, "Requirements for Ethernet VPN
(EVPN)", RFC 7209, DOI 10.17487/RFC7209, May 2014,
.
[RFC7348] - Mahalingam, M., Dutt, D., Duda, K., Agarwal, P., Kreeger,
L., Sridhar, T., Bursell, M., and C. Wright, "Virtual
eXtensible Local Area Network (VXLAN): A Framework for
Overlaying Virtualized Layer 2 Networks over Layer 3 Networks",
RFC 7348, DOI 10.17487/RFC7348, August 2014, .
D. Eastlake, et al [Page 14]
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Authors' Addresses
Donald E. Eastlake, 3rd
Futurewei Technologies
2386 Panormaic Circle
Apopka, FL 32703 USA
Phone: +1-508-333-2270
Email: d3e3e3@gmail.com
Zhenbin Li
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: lizhenbin@huawei.com
Shunwan Zhuang
Huawei Technologies
Huawei Bld., No.156 Beiqing Rd.
Beijing 100095
China
Email: zhuangshunwan@huawei.com
D. Eastlake, et al [Page 15]
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